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Vaccines can have major impact on bacterial meningitis worldwide

More widespread use of the vaccines currently available to treat bacterial meningitis could have a major impact on the disease, according to a global research review led by the University of Sydney.

"Substantial challenges remain, but the good news is that the use of targeted vaccines, especially in parts of the world where the burden of this terrible disease is the heaviest, can have a major effect," said Professor Peter McIntyre, lead author of the review published in The Lancet on Friday.

"It is a justly feared disease which almost always causes death if untreated and long term disabilities such as hearing loss or brain damage in survivors, especially in the poorest countries."

There are three main species of bacteria responsible for most cases of bacterial meningitis worldwide - haemophilus, pneumococcus and meningococcus.

All three infections can be prevented by vaccines that are highly effective against specific types of each bacterium, but the percentage of total cases which can be prevented differs.

"In countries such as Australia and America where the three vaccines have been in use for some years, the number of meningitis cases for all ages has reduced to only about a third of what it was before the first of the vaccines was introduced," said Professor McIntyre.

The first targeted vaccine, for one type of the haemophilus bacterium, has had the most striking impact with reductions of over 95 percent.

The effectiveness of the haemophilus vaccine is tied to there being only one main type of this bacterium that causes meningitis, almost always in young children.

For pneumococcus and meningococcus, there are many more types that cause meningitis in children and adults and not all those types are covered by the vaccine. However, for both bacteria, giving vaccines to children has also led to major reductions in adult disease for the types covered.

"The first and most important challenge is to achieve better delivery of the effective vaccines we already have to difficult-to-access populations at risk in poor countries and to do appropriately designed and executed studies of their impact," Professor McIntyre said.

"There is a critical lack of pre- and post-vaccine data from low- and middle-income countries, such as Africa, where vaccine introduction is recent or is yet to occur."

"The next big challenge, in rich and poor countries, is to develop and test improved vaccines.

"The ability to protect against the greatest range of bacterial types is an important future goal, especially because of the striking reductions in disease in unimmunised older age groups which can be achieved through vaccination of young children," Professor McIntyre said.